Lock



June 23,1942. K HEYER i 2,287,175

LOCK

Filed May l5, 1940 2 Sheets-Sheet l u 'r f f y f v 4 l INVENTOR J. dy@- BWM - ATTORNEY `une 23, 1942.. F. K. HEYER LOCK Filed vMay 15, 1940 2 Sheets-Sheet 2 INVENTOR J/J. .JL/eje?" BY I ATTORNEY Patented June 23, 1942 g uiTED STATES OFFICE LOCK Frederic K. Heyer, Stamford, Conn., assignor to The Yale & Towne Manufacturing Company, Stamford, Conn., a corporation of Connecticut Application May 15, 1940, Serial No. 335,285

(Cl. 'l0-362) 23 Claims.

This invention relates to a tumbler lock of the type especially adapted to resist picking. More particularly, this invention relates to a cylinder lock of the type having tumblers which must be properly set in order to permit rotation of the key plug in which the tumblers are mounted.

Those skilled in the art will fully appreciate that for many years attempts have been made to develop a lock of the type described which would resist the picking or setting of the tumblers by an instrument other than the key. My invention contemplates the construction of a tumbler lock in Which the tumblers are adapted to be set Without relation and without contact with the key plug locking mechanism, it being only after predetermined rotation of the key plug to a point where the tumblers are no longer capable of proper manipulation that the locking mechanism is moved into release position, which movement is possible only if the tumblers were properly set before the said rotation of the key plug.

More particularly, my invention comprises a lock of the type having a series of pin tumblers C incorporated within a key plug and adapted for setting by a key inserted into the key plug. A locking bar is normally positioned for movement out of locking position and into release position when the tumblers are aligned properly; preferably, when a series of release slots in the tumblers are aligned in particular relation to one another and the locking bar.

As a feature of my invention, I utilize means for maintaining the locking bar in locking position and away from the tumblers until the key plug has been rotated to a predetermined position, thereby making it impossible to feel the location of the release slots. After movement to said predetermined position in which the locking bar moves towards the tumblers, I arrange to lock the tumblers against movement as by a picking tool. This last result may be obtained by allowing the movement of the locking bar into false relatively shallow slots of the several A tumblers, rather than into the deeper release slots, it being the function of the locking bar When in the shallow slots to prevent all movement of the tumblers. It is only upon return of the key plug to locked position that the locking bar is once again moved away from the tumblers and into full locking position, whereupon, of course, it becomes again impossible to feel the release positions of the tumblers.

As a further feature of my invention, I utilize a novel form of locking bar adapted preferably for endwise sliding movement relatively to the key plug and into locking relation to a suitable slot in the cylinder. As a matter of fact, in the preferred embodiment of my invention, I utilize two slots in the cylinder in which the locking bar rests, the slots being considerably wider than the bar whereby to allow for a limited free rotation of the key plug. It is subsequent to this limited free rotation that the locking bar is released for movement out of locking position, and will so move if the tumblers will permit it, all as above set forth generally.

A still additional feature of my invention is the means whereby the locking bar is held in locking position to allow free movement of the tumblers when the key plug is in its locked position. Preferably, this means is a control pin movable as the key plug moves relatively to the cylinder, to release the locking bar for movement out of locking position after limited rotation of the key plug, and to later return the locking bar to locking position.

A further important feature of my invention is the arrangement whereby the tumblers are never subjected to pressure, either by attempts to rotate the key plug without iirst properly positioning the tumblers, or through pressure as by a locking bar exerted against the tumblers.

A further feature of my invention is the means whereby the key plug is assembled to the cylinder and with the locking bar in proper relation to the key plug and cylinder.

I have thus described my invention generally prior to describing a preferred detailed modification thereof in order that the basic conception of my invention shallbe clearly understood, it being appreciated that those skilled in the art and understanding the basic conception of my invention will readily develop other structures for utilizing that basic conception.

I shall now describe the drawings wherein is shown a preferred embodiment of my invention. Fig. 1 is a vertical section through a key plug and cylinder of my improved pin tumbler lock. Figs. 2, 3 and 4 are respectively sections along lines 2 2, 3 3 and 4 4 of Fig. 1. Fig. 5 is a rear view of the cylinder of Fig. 1 with certain parts broken away. Fig. 6 is a perspective view taken in section similar to that of Fig. 1, and showing the tumblers properly set with the locking bar moved out of locking position. Fig. 7 is a perspective View of the key plug of my lock, while Fig. 8 is a perspective View of the locking bar. Figs. 9 and 10 are respectively plan and sectional views of the retainer plate utilized in assembling the parts of my invention.

Referring now more particularly to the drawings, the cylinder of my lock is designated by reference numeral It, and has mounted therein a key plug I I of the type having a keyway I2 and a series of tumbler bores I3. Mounted in each of the tumbler bores is a spring I4 and a tumbler I5, it being the function of the key K to move the several tumblers against the pressure of the springs Irl, as best illustrated in Fig. 6. A retaining plate IIa retains the tumblers and springs within their bores I3, as is standard pra-ctice in the art.

Each of the tumblers is equipped with a series of shallow slots I5 and one relatively deep slot Il, the shallow slots being false slots utilif'ed as hereinbefore described generally, and the relatively deep slots I'I being the release slots. Those skilled in the art will understand that for master key work, some of the tumblers may be formed with two or more deep release slots.

It will be appreciated that in the release position of the tumblers, as shown in Fig. 6, the relatively deep slots Il are all in alignment for cooperation with a locking bar I3, which is best illustrated in perspective in Fig. S. This locking bar I8 is equipped with a series of bores I9 which are of a diameter slightly greater than the diameter of the several pin tumblers I5, so that when the locking bar I8 is held in its locking position of Figs. l and 2, the bores I9, being then in correct alignment with the tumblers I5, will allow for free sliding movement of the tumblers. In

this way, the tumblers may be set without any hindrance from the locking bar, all as will be explained more fully hereinafter.

It will be noted that in alignment with the bores I9 of the locking bar I8 there are counterbores 2B, so formed that when the locking bar is released to move to unlocking position, as will later be described, the counterbored portions 213 will enter the several release slots Il, all as is best shown in Fig. 6. It will be noted also that the locking bar IB is equipped with a further bore 2l, which bore cooperates with a control pin 22 to be described presently.

As will be noted from the drawings, the locking bar IS rides in a slot Ia formed in the key plug, and when in locking position has its end portion 23 within opposed slots 24 formed in the cylinder, and best illustrated in Fig. 4. As will be noted from that figure, the opposed slots 24 are of such width relatively to the end surface 23 of the locking bar I3, as to allow for some free rotation of the key plug and locking bar relatively to the cylinder Il), even when the locking bar remains within the slots 2d.

One end of a spring 25 presses against the end surface 23 of the locking bar and tends to move the locking bar toward the tumblers I5. The other end of the spring 25 is maintained in operating position by a spring retainer 25 which ts within a slot Ib of the key plug, forming an extension of the main slot Illa in which the locking bar I8 is mounted.

A substantially U-shaped retainer plate 2'! (Fig. 9) is adapted to slip over the end of the key plug II with its legs moving into the retainer slots 28, best illustrated in Fig. '7, whereby to the spring retainer 25 so that the spring 25 tends to force the surfaces 3S of the spring retainer 2B into the slots 29. In this way, the retainer plate is maintained against movement out of the slots 28 while itself maintaining the spring retainer 25 in proper relation to the key plug. It may therefore be said that the spring retainer 25 and the retainer plate 2l are mutually selfretaining relatively to the key plug.

An operating cam 3| is secured on the key plug I I, by being slipped over the cam flats 32 of the key plug, as best illustrated in Figs. 5 and 7, it being of course understood that the retainer plate 21 also functions to maintain the cam IBI against movement off the key plug flats, all as will be well understood by those skilled in the art.

From the description of the invention so far set forth, it is apparent that my lock has a key plug in which are retained a series of pin tumblers I5 adapted to be set as by a key K so as to align their relatively deep release slots I1 relatively to a locking bar I8, which locking bar I8 is normally pressed by the spring 25 against the several tumblers tending to move the counterbored portions 2il of the locking bar into that relationship with the tumblers illustrated in Fig.

6, and in which relationship the locking end surface 23 of the locking bar will be withdrawn from the locking slots 24 of the cylinder.

It is a feature of my invention, which is of exceeding importance, that the locking bar is maintained away from the tumblers to allow their free movement so long as the key plug remains in an initial locked position illustrated in Figs. l, 2 and 4. For so maintaining the locking bar, I utilize the control pin 22 heretofore described generally. This control pin is equipped with an end pin portion 35 which rests within a cup-like member 36 mounted in a bore 31 formed in the key plug, as best seen in Fig. 3. A spring 'la cooperates with the end pin portion 35 tending to press the control pin 22 upwardly into the position of Figs. 1 and 3.

In the position of the several parts in Figs. 1 and 3, a surface 33 of the control pin 22 cooperates with the bore 2l of the locking bar I8 to maintain the locking bar in its locked position and against the endwise pressure of the spring 25. Also, in the particular position of the parts a control ball 39, resting in a depression 4Q of the control pin 22, is forced upwardly into a bore d! of the cylinder Ill. So long as the ball 39 is within the bore 4I, as in Figs. l and 3, and until it is moved almost completely out of the bore 4I through rotation of the key plug as to the position of Fig. 6, the control pin 22 through the cooperation of its surface 38 or of the cam surface 33a leading to the surface 3B, maintains the end 23 of the locking bar I8 within the locking slots 24 so as to prevent free rotation of the key plug relatively to the cylinder except within the limits of the width of the locking slots 24.

When the key plug has been rotated to the position of Fig. 6 relatively to the cylinder IB, the control ball 39 has been cammed out of the bore 4I, moving the control pin 22 until its neck portion 22a is opposite the locking bar I8. The locking bar I8 is then propelled by its spring 25 so as to bring its countersunk portions 20 within the deep release slots I'I of the several tumblers I5. This, of course, moves the end surface 23 of the locking bar I3 completely out of the locking slots 24, and free movement of the key plug is now possible.

The action above set forth presupposes that the several tumblers I5 have been properly set by the key K prior to any rotation of the key plug from the position of Fig. 1 to the position of Fig. 6. If the tumblers have not been properly set, then the relatively deep release slots I'I will not be all entirely aligned with the locking bar I8, and the locking bar I8 when released by the control pin 22 will move into the relatively shallow slots I6. When so moved, the end locking surface 23 of the locking bar I8 will not move completely out of the locking slots 24 of the cylinder, and therefore, the key plug will not be released relatively to the cylinder for free rotation.

If, in the position of the key plug and its tumblers I just described, it is attempted to manipulate the tumblers to fully release the locking bar I8, it is obvious that the square form of the shallow slots I6 of the tumblers, cooperating with the counterbored surfaces of the locking bar I8, will prevent any up and down movement of the tumblers, making it impossible to pick the tumblers or to feel out the release slots II of the tumblers. In fact, it is apparent that in order to release the tumblers so that they may be manipulated, it is necessary to rotate the key plug II back to its position of Figs. 1 and 3, so that the control ball 39 may enter the bore 4I of the cylinder, allowing the control pin 22 to move upwardly under the iniiuence of its spring 'ia, so that the surfaces 38a and 38 of the control pin may move the locking bar I8 back into its locking position. This carries the counterbored portions 25 of the locking bar out of -the slots of the several tumblers and releases the tumblers for manipulation.

It is thought that those skilled in the art will now fully appreciate the nature of the contribution which I have made to the art. They will fully appreciate that it is absolutely impossible to feel the release position of the several tumblers relatively to the locking bar in the locked position of the key plug because the locking bar is maintained away from the tumblers by the control pin 22. They will fully appreciate that when the control pin 22 releases the locking bar for movement against the tumblers and into the slots of the tumblers, the tumblers are locked so that they cannot be manipulated, the locking bar being held in the deep release slots or in the shallow slots, and preventing any movement of the tumblers. They will further understand the feature that in the locked position of the key plug, it is impossible to apply pressure against the tumblers in any way and that all resistance to rotation of the plug is contributed by the locking bar. Those skilled in the art will fully appreciate also the manner in which my key plug, locking bar, and other parts are assembled relatively to the cylinder, and retained therein by the retaining plate 2'I, all as has been clearly set forth.

I now claim:

l.. In a lock of the class described, a cylinder, a key plug rotatably mounted in said cylinder and having a keyway, tumblers adapted to be positioned by a key inserted into said keyway, a locking member for locking said key plug against free rotation relatively to said cylinder, said tumblers having slots into which said locking member is adapted to enter whereby to release said key plug for rotation, means for moving said locking member into said tumbler slots, and means for maintaining said locking bar out of said tumbler slots until said key plug is rotated relatively to said cylinder.

2. In a lock of the class described, a cylinder, a key plug rotatably mounted in said cylinder and having a keyway, tumblers adapted to be positioned by a key inserted into said keyway,

a locking member for locking said key plug against free rotation relatively to said cylinder while permittinga predetermined degree of rotation, said tumblers having slots into which said locking member is adapted to enter whereby to release said key plug for rotation, a spring pressing said locking member towards said tumbler slots, and means for maintaining said locking member away from said tumblers and out of said tumbler slots until said key plug has been rotated relatively to said cylinder as permitted by said locking bar.

3. In a lock of the class described, a cylinder, a key plug rotatably mounted in said cylinder and having a keyway, tumblers adapted to be positioned by a key inserted into said keyway, a locking bar carried by said key plug and cooperable with a slot in said cylinder for locking said key plug against free rotation relatively to said cylinder while allowing limited rotation of said key plug as determined by the relative widths of said bar and slot, said tumblers having slots into which said locking bar is adapted to enter whereby to release said key plug for rotation, and means for maintaining said locking bar out of said tumbler slots until said key plug has been rotated relatively to said cylinder.

4. In a lock of the class described, a cylinder, a key plug rotatably mounted in said cylinder and having a keyway, tumblers adapted to be positioned by a key inserted into said keyway, a locking bar carried by said key plug and cooperable with a slot in said cylinder for locking said key plug against free rotation relatively to said cylinder while al1-owing limited rotation of said key plug as determined by the relative widths of said bar and slot, said tumblers having slots into which said locking bar is adapted to enter whereby to release said key plug for rotation, a spring pressing said locking bar into said tumbler slots and out of said cylinder slot, and means for maintaining said locking bar out of said tumbler slots until said key plug has been rotated relatively to said cylinder.

5. In a lock of the class described, a cylinder, a key plug rotatably mounted in said cylinder and having a keyway, a series of key set tumblers within said key plug adapted for positioning by a key inserted into said keyway, means interlocking said key plug and said cylinder to lock said key plug against substantial rotation relatively to said cylinder while permitting some predetermined rotation, spring means pressing said interlocking means out of interlocking relation, said tumblers having portions obstructing the movement of said interlocking means out of interlocking relation., but being movable by key to position deep or shallow slots opposite said interlocking means whereby to allow said spring means to press the interlocking means ially or fully out of interlocking relation, and means independent of the tumblers for maintaining said interlocking means away from tumblers against the opposition of said spring until the plug rotates from locked position as permitted by said interlocking means.

6. In a lock of the class described, a cylinder, a key plug rotatably mounted in said cylinder, a series of key set tumblers in said ke?.7 plug, a locking bar in said key plug` extending therefrom into a locking slot in said cylinder to lock said key plug against substantial rotation while permitting a limited degree of rotation, said tumblers having slots into which said bar moves whereby to withdraw said bar from said locking slot, a spring for projecting the bar into said tumbler slots, means for maintaining said locking bar in locking position and away from said tumbler slots until said limited rotation is imparted to the plug, whereupon said locking bar moves into said tumbler' slots and out ol said locking slot to allow further rotation of said key plug, said means acting to move said locking bar out oi said tumbler slots and back into said looking slot when the plug is rotated into its locked position.

7. In a lock of the class described, a cylinder, a key plug rotatably mounted in said cylinder, a series of key set tumblers in said key plug, a locking bar in said key plug extending therefrom into a slot in said cylinder to lock said key plug against substantial rotation while permitting some predetermined rotation, said tumblers having slots into which said bar moves whereby to withdraw said bar from said locking slots, and

ialse shallow slots into which said bar moves a distance not suicient to withdraw it from said locking slot, a spring for projecting the bar into said tumbler slots, means for maintaining said locking bar in locking position and away from said tumbler slots until said predetermined rotation is imparted to the plug, whereupon said locking bar is released by said means to move into said tumbler slots and away from said locking slot.

8. In a lock of the class described, a cylinder, a

key plug rotatably mounted in said cylinder, a series of key set tumblers in said key plug, a locking bar in said key plug extending therefrom into a slot in said cylinder to lock said key plug against substantial rotation while permitting a limited degree of rotation, said tumblers having slots into which said bar moves whereby to withdraw said bar from said locking slot, a spring for projecting the bar into said tumbler slots, means for maintaining said locking bar in locking position and away from said tumbler slots until said limited rotation is imparted to the plug, whereupon said locking bar moves into said tumbler slots and out of said locking slot to allow further rotation of said key plug, said tumblers having shallow slots into which said bar enters when said tumblers have not been properly set prior to said limited rotation, said shallow slots being square whereby to prevent camming of said locking bar out of said slots by pressure against said tumblers.

9. In a lock of the class described, a cylinder, a key plug rotatably mounted in said cylinder, a series of key positioned tumblers in said key plug, a locking member for locking said key plug against release rotation relatively to said cylinder while allowing some predetermined rotation, said tumblers having deep slots into which said member moves whereby to free said key plug for release rotation, and shallower false slots into which said member enters if said tumblers are not properly set, means pressing said member toward said tumbler slots, and means for maintaining said locking member away from said tumbler slots until the said predetermined rotation is imparted to said plug.

l0. In a lock of the class described, a cylinder, a key plug rotatably mounted in said cylinder, a series of key positioned tumblers in said key plug, a locking member for locking said key plug against release rotation relatively to said cylinder while allowing some predetermined rotation, said tumblers having slots into which said member moves whereby to free said key plug for release rotation, a spring for pressing said member into said tumbler slots, means for maintaining said locking member away from said tumbler slots against the pressure of said spring until the said predetermined rotation is imparted to said plug and for thereafter releasing said member, after which said locking member moves into said tumbler slots to allow free rotation of said key plug, said means effecting the movement of said locking member back to locking position against the pressure of said spring upon rotation of said key plug back to said locking position.

11. In a lock of the class described, a cylinder, a key plug rotatable in said cylinder, a series of key set tumblers, a locking bar mounted on said key plug and slidable endwise thereof, a portion of said bar extending into a locking slot in the cylinder for locking the key plug against substantial rotation, said slot allowing limited rotation of said key plug and its locking bar, slots in said tumblers into which portions of said locking bar move when said locking bar is moved out of said locking slot, a spring normally pressing said locking,l bar towards said tumbler slots and out of said cylinder locking slot, a control piece maintaining said locking bar in the cylinder locking slot against the said spring pressure while said key plug remains in locked position, said control piece releasing said locking bar for movement into said tumbler slots when said key plug is rotated towards release position whereby said locking bar enters said tumbler slots if they have been properly aligned prior to rotation of said key plug, said control piece moving said locking bar out of said tumbler slots when said key plug is rotated back to locked position.

l2. In a lock of the class described, a cylinder, a key plug rotatable in said cylinder, a series of tumblers in said key plug and movable therein by a key, a locking bar mounted on said key plug and slidable endwise thereof, one end of said bar extending into a locking slot in the cylinder for locking the key plug against substantial rotation, said slot allowing limited rotation of said key plug and its locking bar, slots in said tumblers into which portions of said locking bar move when said locking bar is moved out of said locking slot, a spring pressing said locking bar towards said tumbler slots and out of said cylinder locking slot, a control piece maintaining said locking bar in the cylinder locking slot against the said spring pressure while said key plug remains in locked position, means whereby said control piece releases said locking bar for movement into said tumbler slots when said key plug is rotated towards release position whereby said locking bar enters said tumbler slots if they have been properly aligned prior to said rotation of said key plug, said tumblers having shallow false slots into which said locking bar enters if said tumblers are not properly positioned, said shallow slots being so related to said locking bar that while said locking bar is in said slots said tumblers cannot be moved.

13. In a lock of the class described, a cylinder, a key plug rotatable in said cylinder, a series of tumblers in said key plug and movable therein by a key, a locking bar mounted on said key plug and slidable endwise thereof, one end of said bar extending into a locking slot in the cylinder for locking the key plug against substantial rotation, said slot allowing limited rotation of said key plug and its locking bar, slots in said tumblers into which portions of said locking bar move when said locking bar is moved out of said locking slot, a spring pressing said locking bar towards said tumbler slots and out of said cylinder locking slot, a control pin spring pressed into position to maintain said locking bar in the cylinder locking slot against said spring pressure so long as said Key plug remains in its locked position, a ball lying partially in said key plug against said control pin and partially within an opening in said cylinder, rotation of said key plug forcing said ball entirely within the key plug and depressing said pin so as to release the locking bar for entry into said tumbler slots if they have been properly aligned prior to said rotation of said key plug, whereby to allow further rotation of said key plug, said ball entering the cylinder opening when the key plug rotates back to locking position whereupon said control pin moves the locking bar out of the tumbler slots and into the said cylinder locking slot.

14. In a lock of the class described, a cylinder, a key plug rotatable in said cylinder, a locking bar in said key plug having a portion thereof eX- tending into a square locking slot in the cylinder whereby said slot exerts no camming force on said locking bar, said slot being or considerably greater width than said locking bar whereby to allow limited rotation oi said key plug relatively to said cylinder and locking slot.

15. In a lock of the class described, a cylinder, a key plug rotatable in said cylinder, a locking bar in said key plug having a portion thereof extending into a locking slot in the cylinder, said slot being of considerably greater width than said locking bar whereby to allow limited rotation oi said key plug relatively to said cylinder and locking slot, a spring pressing said locking bar outwardly of said slot whereby to release the key plug for free rotation relatively to said cylinder, and a control piece maintaining said locking bar within said slot against the pressure of said spring while said key plug remains in locking position.

16. In a look of the class described, a cylinder, a key plug rotatable in said cylinder, a locking bar in said key plug having a portion thereof extending into a locking slot in the cylinder for locking said key plug against free rotation while permitting a limited degree of rotation relatively to said cylinder, a spring pressing said locking bar outwardly oi said slot whereby to release the key plug -ior free rotation relatively to said cylinder, a control piece maintaining said locking bar within said locking slot against the pressure of said spring while said key plug remains in locking position, and means for moving said control piece as said key plug rotates relatively to said cylinder as allowed by said locking slot whereby to release said looking bar for movement by its spring out of said locking slot.

17. In a look of the class described, a cylinder, a key plug rotatable in said cylinder, a locking bar in said key plug having a portion thereof extending into a locking slot in the cylinder for locking said key plug against free rotation while permitting a limited degree of rotation relatively to said cylinder, a spring pressing said locking bar outwardly of said slot whereby to release the key plug for free rotation relatively to said cylinder, a control piece maintaining said locking bar within said locking slot against the pressure of said spring while said key plug remains in locking position, and means for moving said control piece as said key plug rotates relatively to said cylinder as allowed by said locking slot whereby to release said locking bar for movement by its spring out of said locking slot, and key set tumblers for preventing movement of said locking bar out of said locking slot unless said 'tumblers have been key set in proper alignment.

18. In a lock of the class described, a key plug, a series of tumbler bores in said key plug, tumblers in said bores, a slot in said key plug transverse of said tumbler bores, a locking plate in said slot, a series of openings in said plate formed therein so as to lie in alignment with the tumbler bores, slots in said tumblers into which said plate is movable, and means for moving said plate endwise of said key plug with portions thereof entering into said tumbler slots when they are properly aligned through manipulation of the tumblers.

19. In a look of the class described, a cylinder, a key plug rotatable in said cylinder, a control pin mounted in a bore in said key plug, a spring pressing said pin upwardly toward said cylinder, 4

and a ball in said bore resting against the end of the control pin and lying partially in a functionally shallow opening in said cylinder, whereby upon rotation of said key plug said ball will be forced entirely within the bore of said key plug.

20. In a lock oi the class described, a cylinder, a key plug rotatable in said cylinder, a control pin mounted in a bore in said key plug, a spring pressing said pin upwardly toward said cylinder,

a ball in said bore resting against the end of the control pin and lying partially in a functionally shallow opening in said cylinder, whereby upon rotation of said `key plug said ball will be forced entirely within the bore of said key plug, and a locking member for said key plug moved by said control pin as it in turn is moved relatively to the cylinder.

21. In a lock of the class described, a cylinder, a key plug rotatably mounted in said cylinder and having a keyway, tumblers mounted for movement entirely within said key plug and adapted to be positioned by a key inserted into said keyway, a locking member mounted on said key plug and cooperable with portions of said cylinder for locking said key plug against free rotation relatively to said cylinder, said tumblers having slots into which said locking member is adapted to enter whereby to release said key plug for rotation, means for moving said locking member into said tumbler slots, and means for maintaining said locking member out of said tumbler slots until said key plug is rotated relatively to said cylinder.

22. In a lock of the class described, a cylinder, a key plug rotatably mounted in said cylinder and having a keyway, tumblers mounted for movement entirely within said key plug and adapted to be positioned by a key inserted into said keyway, a locking member mounted on said key plug and cooperable with portions of said cylinder for locking said key plug against free rotation relatively to said cylinder while permitting a predetermined degree of rotation, said tumblers having slots into which said locking member is adapted to enter whereby to release said key plug for rotation, a spring pressing said locking member towards said tumbler slots, and means for maintaining said locking member away from said tumblers and out of said tumbler slots until said key plug has been rotated relatively to said cylinder as permitted by said locking member.

23. In a lock of the class described, a cylinder, a key plug rotatably mounted in said cylinder and having a keyway, tumblers adapted to be positioned by a key inserted into said keyway, a locking member for locking said key plug against free rotation relatively to said cylinder, said tumblers having slots into which said locking member is adapted to enter whereby to release said key plug for rotation,v means for moving said locking member into said tumbler slots, control means other than said tumblers for maintaining said locking member out of said tumbler slots, and means for releasing said locking member from said control means.

FREDERIC K. HEYER. 

